(written from a Production point of view)
Hal Sutherland directed the 16 episodes of TAS Season 1 of Star Trek: The Animated Series. Sutherland's name appears in the closing credits of each episode of TAS Season 2. However, Filmation used stock closing credit sequences. Bill Reed was the director for Season 2 as stated in the episode title page at the beginning of each episode.
NBC's decision for Filmation to be the studio that would produce the animated Star Trek was somewhat daunting for Hal Sutherland. "[It] was quite an honor, and scared the devil out of me a little bit," he recalled, with a laugh. Sutherland found that the actual production of the show was likewise a mixed experience, later saying of the series, "It was really different and it was a pleasure to work on, but frightening at the same time because you really didn't wanna do a lesser job than the public might expect." ("Drawn to the Final Frontier - The Making of Star Trek: The Animated Series", TAS DVD)
Hal Sutherland has a kind of color blindness that attributed to numerous color issues in the series. The art department compensated for this except for in "The Slaver Weapon", which features the pink-colored craft Traitor's Claw, and in "More Tribbles, More Troubles", in which the tribbles are also unintentionally pink.
Ultimately, Hal Sutherland was pleasantly surprised by NBC's elation with the series. "I remember getting a personal letter from them saying how wonderful the show looked and how happy they were at the results. I'd never heard anything like that in all the years we'd been in business, 20 odd years," concluded Sutherland, laughing. ("Drawn to the Final Frontier - The Making of Star Trek: The Animated Series", TAS DVD)